Coating of parts of a liquid toner imaging system in order to avoid agglomerations of toner particles, colloquially known as “sludge”, is well known. In general, such coatings comprise silicone or fluorosilicone materials. Surfaces normally treated include surfaces to which the toner would normally plate due to an electric field, metal surfaces on which the toner sits for extended periods of time or in regions in which the toner is subjected to other types of stress.
In WO 90/05941, the disclosure of which is incorporated herein by reference, coating of surfaces onto which toner particles would plate, due to an electric field, is described. The coatings described include fluorosilicones and ZONYL a brand name for a series of Dupont fluorosurfactants. The ZONYL material is described (incorrectly) as a fluorosilicone. With respect to the use of ZONYL as a coating the reference states “Alternatively, coating the developer electrode with fluorosilicone surfactants such as ZONYL (DuPont) has been effective in inhibiting plating out of toner particles, but this expedient inhibits plating-out of toner particles for only a limited period of time.”